Closed cycle steam engines used for example in propelling underwater vehicles such as torpedos are many and varied in design. Typical of such a system is the steam boiler-reactor disclosed in U.S. Pat. No. 3,964,416. Elongate pyrotechnic starting charges extend through a fuel, in this case cast lithium, to initiate combustion and a consequent creation of steam. The elongate pyrotechnic starting charges consist of a mixture of finely divided aluminum and potassium perchlorate. Those who have worked with and are experianced with such mixtures have learned that the mixtures may be susceptible to becoming even more finely powdered and, therefore, more susceptible to the possibility of an unintentional ignition that may be due to electrostatic discharge,ignition by mechanical friction or other means. Another undesirable possibility is that when a planned ignition is initiated, the ignition might progress at a much higher, violent burn rate than is intended for a proper ignition of a preferred fuel.
In some later closed-cycle boiler designs the columns of ALCLO have been replaced by tablets which are placed in a cavity within the boiler. However, it has been noted that handling and the vibrating environment causes some settling to occur and the tablets rub against each other. This causes the generation of powdered ALCLO which is far easier to ignite than the pellet form so that the possibility, of an accidential ignition by electrostatic discharges ignition by mechanical friction or other means. Or a higher, explosive burn rate may result after an intentional ignition.
A combustion system disclosed in U.S. Pat. No. 3,056,701 uses aluminum foil to perform both mechanical and fuel functions. Aluminum foil disks separate powdered packages of fuel materials. Modifications of the disk use separate packages, like soup bags, to contain the powdered fuel materials. The powdered form of the fuel materials is retained to assure an intense and vigorous actuation for such uses as artillery rockets and the like. The powdered from of the fuel assures such a intense and vigorous burning which is encouraged for the intended use.
Thus, a continuing need exists in the state of the art for a method or means of preventing the inadvertent powderinq of explosive ALCLO tablets used in a torpedo boiler.